Preventing fuel contamination in pipelines



United States Patent 3,325,310 PREVENTING FUEL CONTAMINATION IN PIPELINES Maurice R. Barusch, Richmond, Calif., assignor to Chevron Research Company, a corporation of Delaware No Drawing. Filed Jan. 28, 1963, Ser. No. 254,496 3 Claims. (Cl. 134-22) This invention relates to an improvement in the transportation of liquid petroleum products through pipelines and their corresponding equipment, such as valves, pumps, etc. In particular, it relates to an improvement in the transportation of petroleum fuels used for the propulsion of motor vehicles and aircraft as well as for heating purposes. These fuels which comprise various hydrocarbon distillate stocks, such as gasolines, kerosene, gas oil, furnace oil and heating oils, are transported from refineries to storage plants and distribution terminals, such as airfields, wharves, etc., whence they are distributed as fuels to individual vehicles and aircraft and also for heating and other industrial uses.

It is a common practice to introduce at the refinery relatively minor amounts of additive materials into a hydrocarbon stock or a fraction intended for use as a fuel in order to impart thereto certain characteristics which are desirable for the particular use. Many of these additives are surface-active. For instance, several detergent-action aminoalkylene amides are currently employed by the industry in miner amounts in gasolines to reduce engine deposits and also as corrosion inhibitors. Likewise, derivatives of various alkyl amines, alkylene diamines, carboxylic acids, organic phosphoruscontaining compounds, polymeric materials, and a large number of other surface-active additives are combined with petroleum hydrocarbon stocks which are intended to be sold and used as engine fuels and/ or illuminating and heating oils.

It has been noted that the surface-active constituents (-both those normally present in petroleum stocks and the additives) of such petroleum hydrocarbon fuels tend to become adsorbed on the interior surface (wall) of the pipe. When a particular delivery or a tender of a fuel is completed and a new tender of a different stock is sent next through the line, the adsorbed surfaceactive materials are gradually removed (desorbed) from the surface of the line, pass into the stream of the new tender of fuel and are carried away with it.

This subsequent fuel tender so contaminated by the desor-bed surface-active materials may be, for instance, a petroleum distillate fuel of substantially the same nature, such as a tender of gasoline which follows a tender of a similar gasoline but boiling within a wider or a narrower boiling range. Or yet, this subsequent tender may be, for instance, a gas oil containing (or lacking) an additive, the presence (or absence) of which imparts a certain property desirable in this fuel for the particular ultimate use.

When surface-active materials which left the first fuel tender to deposit themselves on the wall of the pipeline are removed therefrom on contact with the subsequent, second tender of a similar fuel intended for use in stationary engines or in motor vehicles on land, the presence of these surface-active contaminants in the fuel when it arrives at its destination may and should result in its non-acceptance for failure to comply with the specifications for this fuel.

In particular the presence of surface-active contaminants in a fuel generally has an extremely adverse effect upon its water tolerance properties and is responsible for the rejection of such a fuel both by the private industry and by the military.

Petroleum fuels, particularly those for use in air-craft, must be free of water since the presence of water is apt to result in condensation and ice formation, plugging filters and restricting the flow of fuel to the engine. The water reaction or water tolerance must be such that after a measured amount of the fuel ml.) is shaken vigorously with a measured amount of distilled water (20 ml.) for 2 minutes at room temperature, the fuel shall separate sharply from the water layer within five minutes, and there shall be no evidence of an emulsion, precipitate or suspended matter within or upon either layer.

Far more serious consequences may and do occur when, of the two tenders of petroleum fuels which follow each other, the second tender, whether a gasoline or a kerosene-type jet fuel, is intended for use in aircraft. In this instance, the presence of undue surfaceactive contaminants desorbed from the surface of the pipeline likewise may and should result in non-acceptance of the particular contaminated tender. Moreover, if, through inadvertence or oversight, the fuel contaminated with surface-active materials should be accepted, without ascertaining that it passes the water tolerance test described in Federal Test Standard No. 791 under Method 3251.6, and should be permitted to fill the fuel tanks of an aircraft, the presence of the surface-active contaminants is apt to cause plugging of the fuel filters, the fuel feed lines and other fuel conveying equipment of the aircraft, thereby contributing to malfunctioning of the engine, increasing the hazard of explosion and jeopardizing human lives.

The present invention, as hereinafter described in detail, is directed to an improvement in the use of pipelines, which permits transporting different tenders of petroleum fuels without the risk of contaminating subsequent fuel tenders by surface-active materials that might have become adsorbed on the interior surface (wall) of a pipe-. line. The invention thus eliminates contamination of petroleum fuels during their transportation through pipelines from refineries by providing .a method for effective removal of substantial proportions of surface-active contaminants from the walls of the pipelines. The application of this method prevents the failure of these fuels to comply with the specifications and their consequent nonacceptance by the ultimate consumers.

According to the invention surface-active contaminants adsorbed on the interior surface of a pipeline can be desorbed therefrom and effectively removed by introducing into the line an effective quantity of an aliphatic alcohol, preferably a C -C alcohol, as a purging additive. This addition takes place just preceding the beginning of the operations of pumping and conveying a new tender of petroleum. distillate fuel through a pipeline, the interior surface of which has been contaminated (coated) with surface-active materials adsorbed from a preceding tender (or tenders) of fuel. Particularly effective and, accordingly, the most preferred purging additive is isopropanol.

The other preferred operative C -C aliphatic alcohols are ethanol, n-propanol, n-butanol, isobutanol, and the like.

The alcohol purge is introduced into the pipeline either in pure form or yet metered into the fuel entering the line in amounts which may be as low as 0.5% by volume, referred to the volume of the fuel tender flowing through the pipeline at the place of metering in the alcohol. This introduction takes place either before the beginning of the delivery of a new fuel tender or in accordance with an appropriately selected metering. schedule; or yet the purging additive may be added at once into the storage tank which contained the preceding fuel tender at the very instant that this tank is stripped of the fuel and just before commencing the delivery of the new fuel tender into the pipelines.

The effective critical concentration of the alcohol purge, whether added at once (100% by volume) or metered in (at least 0.5% by volume as indicated above), must be so selected that at the delivery end of the pipeline, the alcohol content in the effluent fuel will be at least 0.5% by volume.

For practical purposes, the critical range of amounts of alcohol eifective in accordance with the invention expressed in barrels (42 gallon capacity), extends from about 0.1 to about barrels per each 100' miles of a smooth pipeline of 8' 1D.

In other words, the alcohol will be introduced in amounts in the range from about 0.0001 to about 0.01 barrels per 1000 square feet of the internal surface of pipeline at such a rate that the concentration of the alcohol is at least 0.5% by volume of the fuel charge flowing through at the place of introduction of the alcohol.

As mentioned already, isopropanol is the most preferred as a purging additive among the various saturated C -C aliphatic alcohols.

LABORATORY TESTING A series of laboratory tests were carried out to simulate the conditions in a pipeline transporting petroleum fuels and contaminated by adsorption of surface-active materials. The test apparatus consisted of a 50 ml. glass burette, partially filled with 100 g. of particles (iron filings) of mesh. The surface of these iron filings is believed to be iron oxide. This iron oxide surface of the particles in the burette, as determined by adsorption of nitrogen, corresponded to 0.12 mile of a perfectly smooth 8" pipeline. The contents of the burette were first saturated with surface-active monooleyl amide of hydroxyethylethylenediamine (dissolved in gasoline) tagged with carbon-14. It was determined that about 1.1 mg. of this amino-amide material was adsorbed at equilibrium on 1 In. of the iron oxide surface. The so-saturated iron oxide contents of 'the burette were then eluted with fuels containing saturated C2-C aliphatic alcohols as purging agents in accordance with the invention at a rate of 500 ml./hr.

The liquid fuel recovered from the burette after elution was analyzed to determine the radio-activity, each new elution run being carried out on a freshly prepared (saturated) iron oxide. The results of these analyses clearl'y demonstrated effectiveness of the alcohol purge accord ing to the invention. For example, elution with a synthetic hydrocarbon base fuel (/50 mixture of isooctane and toluene), which contained isopropanol in an amount corresponding to an addition of 3.3 'barrels of the alcohol in a 100 mile pipe of 8' ID. with a surface roughness coefficient of 10, resulted in the removal of as much as 60% of the surface-active contaminants. Likewise, the subsequent passage of a fuel distillate known under the designation of aviation turbo-jet fuel JP-4, which initially conformed with the Water Tolerance Test specifications, such as US. Military Specification MIL-F-56'24D, the like, revealed no change in the water reaction properties of this jet fuel.

Following these laboratory tests, effectiveness of the saturated C -C aliphatic alcohols, and specifically of isopropanol, as agents for purging (removing) surface- ;active contaminants which might have become admixed to petroleum fuels by desorption in the course of their passage through pipelines from the refinery to the distribution plant, was conclusively confirmed in actual practice.

Field Example I A 20,000 barrel tender of commercial automotive gasoline, boiling in the range of about 80' to about 430 F. (ASTMD86) and containing, as a detergent-action additive for the reduction of engine deposits, the surface-active monooleyl amide of hydroxyethylethylenediamine in 4 an amount which corresponded to about 15 pounds of the amide per 1000 barrels of gasoline, was sent through an 8" pipeline a distance of about 190 miles. Samples of this gasoline indicated reduction (loss) of the surface-active amide following its flow through the pipeline.

When this first tender was followed by a new tender of a 115/ 145 aviation gasoline which contained no amide at the beginning of trans-fer, sampling of theefiluent disclosed the presence of a surface-active amide contamination in such proportions as to cause it to fail the Water Tolerance Test and to be rejected. However, when a 10 barrel slug of isopropanol was introduced into the line following a similar tender of an amide treated automotive gasoline, the isopropanol effectively purged the line, and the subsequent tender of an amide-free aviation gasoline fuel (115/145) when tested at the end of the line, was found to pass the required Water Tolerance Test and was accepted for use.

Field Examlple II When a tender of automotive gasoline, such as was mentioned hereinabove in Example I, that is, one boiling in the range of about to about 430 F. and containing the same surface-active amide used in the same proportions, was sent through a like 8" pipeline a distance of about miles, samples of effluent fuel again indicated adsorption (plating) of substantial amounts of the surface-active amide on the interior surface of the pipeline.

A tender of jet fuel which followed this first tender of gasoline, when sampled and tested at the end of the line in accordance with the Water Reaction Test, received a rating of 2, which caused rejection of this jet fuel as not conforming to the Military Specification MILF-56 24D.

On the other hand, when a tender of a similar automotive gasoline containing the surface-acti've amide was followed by a slug of 10 barrels of isopropanol, the immediately following tender of JP-4 fuel upon arrival at the end of the pipeline was found to pass satisfactorily the Water Tolerance Test (Method 3251.6, Federal Test Standard No. 791), meeting the Military Specifications for aviation turbo-jet fuels, and was accepted.

Field Example III In a series of field tests, tenders of 1000 barrels of JP-4 fuel each were sent through a pipeline 12 miles long, after transporting therethrough different distillate fuels which contained surface-active contaminants, such as detergent-action amides, corrosion inhibitors, etc. without the purging treatment with an alcohol in accordwith the invention. The jet fuel in each instance failed to pass the Water Tolerance Test and could not be accepted.

When, however, a purging alcohol, namely, isopropanol, was introduced into the line immediately in front of the jet fuel tender, and in amounts corresponding to 2 barrels, one barrel and /2 barrel, respectively, per each 100 miles of a smooth pipeline of 8" ID., each tender of 1000 barrels of this JP-4 fuel was found to be on test and acceptable as conforming to the Military Specifications. Evidently the objectable surface-active contaminants were effectively removed from the line.

Depending on the nature and the ultimate use of the fuel being transported through the line, the alcohol employed as a purging additive prior to the transportation of that fuel may be either left in it or may be removed therefrom in a conventional manner, as by withdrawing a corresponding front portion of the tender containing the alcohol and pumping it into a slop tank.

In conclusion, it is to be understood that the invention is not to be limited to the specific examples which have been offered for the sole purpose of illustrating the same, and that any variations of the invention which conform with the spirit and come within the scope thereo1f, are includable under the definitions of the following 0 aims.

I claim:

1. Process for removing a member selected from the group consisting of contaminant surface-active higher aliphatic amide and amine fuel additives absorbed on the internal surface of a pipeline for the transportation of liquid petroleum fuels, which comprises introducing into said pipeline so contaminated from about 0.0001 to about 0.01 barrels of a purging additive consisting essentially of a C -C aliphatic alcohol per 1000 square feet of the internal surface of said pipeline at such a rate that the concentration of the introduced alcohol is at least 025% by volume in order to desorb and effectively remove said contaminant surface-active materials.

2. Process as defined in claim 1, wherein said alcohol is introduced into the pipeline immediately before sending a petroleum fuel thereth'rough.

References Cited UNITED STATES PATENTS 8/ 1944 'Lehmann et al. 6/1953 Faulkner 134-20 OTHER REFERENCES Condensed Chemical Dictionary, sixth edition, pp. 627-628, 1961.

MORRIS O. WOLK, Primary Examiner.

15 F. BROWN, Assistant Examiner. 

1. PROCESS FOR REMOVING A MEMBER SELECTED FROM THE GROUP CONSISTING OF CONTAMINANT SURFACE-ACTIVE HIGHER ALIPHATIC AMIDE AND AMINE FUEL ADDITUVES ABSORBED ON THE INTERNAL SURFACE OF A PIPELINE FOR THE TRANSPORTATION OF LIQUID PETROLEUM FUELS, WHICH COMPRISES INTRODUCING INTO SAID PIPELINE SO CONTAMINATED FROM ABOUT 0.0001 TO ABOUT 0.01 BARRELS OF A PURGING ADDITIVE CONSISTING ESSENTIALLY OF A C2-C4 ALIPHATIC ALCOHOL PER 1000 SQUARE FEET OF THE INTERNAL SURFACE OF SAID PIPELINE AT SUCH A RATE THAT THE CONCENTRATION OF THE INTRODUCED ALCOHOL IS AT LEAST 0.5% BY VOLUME IN ORDER TO DESORB AND EFFECTIVELY REMOVE SAID CONTAMINANT SURFACE MATERIALS. 